205421311 has 2 divisors, whose sum is σ = 205421312. Its totient is φ = 205421310.

The previous prime is 205421309. The next prime is 205421327. The reversal of 205421311 is 113124502.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 205421311 - 2¹ = 205421309 is a prime.

Together with 205421309, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (205421341) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 102710655 + 102710656.

It is an arithmetic number, because the mean of its divisors is an integer number (102710656).

Almost surely, 2^205421311 is an apocalyptic number.

205421311 is a deficient number, since it is larger than the sum of its proper divisors (1).

205421311 is an equidigital number, since it uses as much as digits as its factorization.

205421311 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 240, while the sum is 19.

The square root of 205421311 is about 14332.5263299950. The cubic root of 205421311 is about 590.0405133532.

Adding to 205421311 its reverse (113124502), we get a palindrome (318545813).

The spelling of 205421311 in words is "two hundred five million, four hundred twenty-one thousand, three hundred eleven".